The crew of the space shuttle Discovery successfully completed a dress rehearsal today for their upcoming launch. They capped off their practice run at Cape Canaveral with a simulated countdown to liftoff at 11:00 a.m. ET.

The seven STS-124 astronauts are scheduled to launch May 31 at 5:02 p.m. ET to deliver the international space station's largest room, the 32,500-pound Japanese Kibo Laboratory. Crewmembers are slated to perform three spacewalks during their planned 13-day mission.

"This is a big moment in our training to actually go through a real terminal countdown," Discovery's commander Mark Kelly told reporters Thursday. "In this case it's a test, but we do everything that we'd do on launch day."

Yesterday, the astronauts practiced the escape procedures they would use if they had to evacuate the shuttle in the case of an emergency. They rehearsed climbing into and out of the baskets that would zip them quickly away from the launch pad (though they did not actually ride them down, because NASA administrators deem this too much of an unnecessary risk).
Slideshow: Month in Space: January 2014

Today's practice countdown was the last scheduled training exercise at Cape Canaveral until the STS 124 flight. Later at 2:00 p.m. ET the astronauts will head back to Houston to resume preparing for the mission. They plan to arrive back in Florida on May 28.

"We're excited to be here," Kelly said Thursday. "We look forward to getting back in about three weeks from now."